Transparent silicon carbide/tunnel SiO<sub>2</sub> passivation for c‐Si solar cell front side: Enabling <i>J</i><sub>sc</sub> > 42 mA/cm<sup>2</sup> and i<i>V</i><sub>oc</sub> of 742 mV
Manuel Pomaska, Malte Köhler, Paul Prócel, A. O. Zamchiy, Aryak Singh, Do Yun Kim, Olindo Isabella, Miro Zeman, Shenghao Li, Kaifu Qiu, Alexander Eberst, Vladimir Smirnov, F. Finger, Uwe Rau, Kaining Ding
Abstract
Abstract N‐type microcrystalline silicon carbide (μc‐SiC:H(n)) is a wide bandgap material that is very promising for the use on the front side of crystalline silicon (c‐Si) solar cells. It offers a high optical transparency and a suitable refractive index that reduces parasitic absorption and reflection losses, respectively. In this work, we investigate the potential of hot wire chemical vapor deposition (HWCVD)–grown μc‐SiC:H(n) for c‐Si solar cells with interdigitated back contacts (IBC). We demonstrate outstanding passivation quality of μc‐SiC:H(n) on tunnel oxide (SiO 2 )–passivated c‐Si with an implied open‐circuit voltage of 742 mV and a saturation current density of 3.6 fA/cm 2 . This excellent passivation quality is achieved directly after the HWCVD deposition of μc‐SiC:H(n) at 250°C heater temperature without any further treatments like recrystallization or hydrogenation. Additionally, we developed magnesium fluoride (MgF 2 )/silicon nitride (SiN x :H)/silicon carbide antireflection coatings that reduce optical losses on the front side to only 0.47 mA/cm 2 with MgF 2 /SiN x :H/μc‐SiC:H(n) and 0.62 mA/cm 2 with MgF 2 /μc‐SiC:H(n). Finally, calculations with Sentaurus TCAD simulation using MgF 2 /μc‐SiC:H(n)/SiO 2 /c‐Si as front side layer stack in an IBC solar cell reveal a short‐circuit current density of 42.2 mA/cm 2 , an open‐circuit voltage of 738 mV, a fill factor of 85.2% and a maximum power conversion efficiency of 26.6%.